Yes that’s right, it’s that time of the month for everybody’s least favourite astronomy blog: My Tour of the Solar System. This is the fourth amazing entry of the tour, so if you’re new, or you don’t know what to do, I promise it’s ok. The three previous entries are: Meet the Family, The Sun, and Planets vs. Dwarf planets.

When we last left the tour, I was waffling on about the differences between planets and dwarf planets, because you know, dwarf planets are a real thing. Seriously. So because of this, we move onto the first planet from the Sun, Mercury.

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Named after the messenger of the gods in Roman mythology, Mercury is quite odd, considering a few of its siblings are overachievers. Mercury is believed to be 4.5 billion years old, so its quite similar to Earth in age.

Mercury is the smallest planet in our Solar System, with a mean diameter of 4,880 km; which puts it slightly larger than the Moon, at 3,474 km. Basically, if there was an arm wrestle between the two of them, your money should go on Mercury; but keep your cryptocurrency on Earth, because no other planet wants it.

Even though Mercury is the closest planet to the Sun, it is not the hottest; but it’s still worth swiping right. Mercury orbits the Sun at a range of 47 million km (29 million miles) to 70 million km (43 million miles); with an average distance of 58 million km (36 million miles). To put this into perspective, Earth orbits the Sun at an average distance of 150 million km (93 million miles).

Given its proximity to the Sun, Mercury is a hot mess. The length of time it takes for light to travel from the Sun to Mercury, is 192 light seconds or 3.2 light minutes, which is less time to boil an egg.

Temperatures can vary as much as Cookie Monster can eat all of the cookies in a single day. The surface temperatures on Mercury are insanely hot and cold. Day temperatures can reach 430°C (800°F), while night temperatures can plummet to -180°C (-290°F). Because it has no atmosphere, Mercury can’t hold onto the heat during the night, resulting in cold temperatures. Can you imagine the electricity bills?

And like the Flash, Mercury lives up to its namesake. Compared to all of the planets in the Solar System, Mercury is the fastest; even Usain Bolt would be moving like a statue in comparison. Not a Weeping Angel, though. To hell with that.

The further away a planet is from the Sun, the slower it travels; however the opposite is also true. Because Mercury is the closest planet to the Sun, it has the shortest distance to travel around it. This has resulted with Mercury travelling through space at 47 km (29 miles) per second, but it also has some counterintuitive discoveries.

• Mercury spins slowly on its axis, at a rate of once every 59 Earth days.
• It takes 88 Earth days for Mercury to orbit the Sun; which equals one Mercury year.
• It takes 176 Earth days for Mercury to complete one solar Mercury day. Mercury has an elliptical orbit, which means twice during its orbit, it gets quite close to the Sun and speeds up, so it appears the Sun would be going backward; if you were standing on Mercury’s surface.
• This means one day on Mercury, is longer than a Mercury year.

And just to add some more fun stuff; Mercury has no rings, no natural satellites (moons), plus it is tidally locked with the Sun.

Just like Red, Boober, Mokey, Gobo, and Wembley are all Fraggles; Venus, Earth, Mars, and Mercury are all rocky or terrestrial planets. Mercury looks like our Moon, with craters covering the surface, however with the crust and mantle being made of rock, the core is solid iron. This works out to be 75% of Mercury’s diameter. Because of Mercury’s smaller size, when the core cooled down, it become solid, which made Mercury shrink and caused the surface to wrinkle. This didn’t happen to Earth because it was larger, along with the fact our outer core was liquid, and the inner core was solid.

The majority of the craters on Mercury are actually named after famous artists, composers, and writers. The most famous crater is Caloris Planitia, which is an impact basin, stretching 1,550 km (960 miles) in diameter. For perspective, the length of the United Kingdom is about 1,000 km (600 miles). The Caloris Planitia is surrounded by a ring of mountains; and no, they are not the Ash Mountains, nor the Mountains of Shadow; but rather the Caloris Montes, which are 1-3 km high.

Another reason to swipe right, is the fact that Mercury’s mass is less than 6% of Earth’s. This means Mercury’s gravity is weaker, so if you weighed 70 kg on Earth, you would only weigh 26.6 kg on Mercury. Imagine how high you could jump?

Do you remember what I said about Mercury not having an atmosphere? Good job, you were paying attention. Well, Mercury does have a thin exosphere though. This exosphere is mostly made of oxygen, sodium, hydrogen, helium, and potassium. If you could stand on the surface of Mercury without a protective space suit, the cold, heat or just lack of air, would kill you in under 90 seconds. That’s something to put on the tourism brochure!

All and all, Mercury is a special and unique world, but just like visiting the dentist, you really wouldn’t like to go there. And with that, it’s time to wrap up another tour stop of the Solar System. Yah! This coming week, I’m going to be releasing two special short blogs, celebrating two important days on the Geek calendar. Do you know what they are? The first one will be on Thursday, while the second will be on Saturday. Three blogs in a week? I’ll need a lie down to do this.

Thanks once again for reading, following, and subscribing to Some Geek Told Me. Remember to walk your dog; read a banned book; stop running with scissors; and I’ll see you next week.

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